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Cracked engine mount!!

N605RV

Member
The right side motor mount on my RV-4 just above where it attaches to the gear socket is cracked (see photo). I hear this is not uncommon but I'm panicking anyway. Anyone know of a fix and if so, please advise. Perhaps others have made the repair. Weld then install a gusset? If so, anyone have them pre-made? Please advise. photos are appreciated.
Mike in Boulder, N605RV
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Great to have these resources. I’m sure Russ has seen many of these. I have a friend who had a 6 based out of a pretty rough ww2 training airfield. The pavement dated to 1940. He had this happen twice. It is a PITA but nothing to panic over.
 
Yes but

The right side motor mount on my RV-4 just above where it attaches to the gear socket is cracked (see photo). I hear this is not uncommon but I'm panicking anyway. Anyone know of a fix and if so, please advise. Perhaps others have made the repair. Weld then install a gusset? If so, anyone have them pre-made? Please advise. photos are appreciated.
Mike in Boulder, N605RV
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I faced this 2 years ago.
Visually it looked cracked.
After settled down I was advised to do a dye test.
Not really cracked.

When I contacted Russ he said the line was an artifact from where he clamped it during the welding process.
No further issues in the ensuring ~220 hours.

Daddyman
 
Cracked engine mount RV4

Hi Daddyman,
thanks for the uplifting suggestion..I did contact Russ and will have my welder look at it. I was very suspicious of the crack since the line was so straight and so was the AI but when you run your fingernail over it, it was raised just a tad. Sanding it just a little revealed the metal higher one one side at the crack (see photo - did yours do that too?) What dye kit did you use? another simple test I suppose would be to repaint it, fly it a few times and see if it re-cracks the paint, if so, it's a crack.
 
Gosh! That is suspicious and naturally you'll have to get this figure out. I wonder if maybe using a dab of paint stripper to remove the paint might be better than sanding. Maybe then you can better preserve the original mystery that's lying below the paint. I don't know but just a suggestion. I also agree with above post that it's suspiciously straight. Keep us posted.

Edited. Are the mounts powder coated or painted. I don't know. Don't know if stripper will work on powder coated parts.
 
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Would NOT suggest flying as test

There are no successful pessimists ....but I would be every reluctant to fly until I was sure about diagnosis. Flying it as a test would not qualify as prudent I think ....just my two cents worth
 
dye penetrant

any suggestions on which dye to use to check the crack with? Do people still use Magnaflux or is there on that's better.
thanks
Mike in Boulder
 
Hi Mike,

I didn't mention the the other day but until you know for sure this is not broken or until it's repaired it has to be grounded. Right now its just a stress crack, easy to adress, however it's most of the way through, if it releases things are going to be much more difficult.

I don't know what die test to recommend, you can order them online or probably go to your local Airgas store and get one.

Russ
 
Higher on one side?

Hi Daddyman,
thanks for the uplifting suggestion..I did contact Russ and will have my welder look at it. I was very suspicious of the crack since the line was so straight and so was the AI but when you run your fingernail over it, it was raised just a tad. Sanding it just a little revealed the metal higher one one side at the crack (see photo - did yours do that too?) What dye kit did you use? another simple test I suppose would be to repaint it, fly it a few times and see if it re-cracks the paint, if so, it's a crack.

Mike,
I do not remember it being higher as I ran my fingernail over it. I do remember the line being perfectly straight and could feel the line with my fingernail.
Hope it turns out well.

Daddyman
 
Pegasus has a complete kit including the black light,
(HAO) Fluorescent UV Dye Penetrant Crack Testing Kit, $65.99
It's messy, but it works well.
 
Hello, just an update. Yes my engine mount is cracked so now I'll have to remove the engine and have it welded. If anyone has any photos of a similar repair please send. My plan is to b repair it, if possible, to get it airworthy then order a new mount.
Thank you everyone.
Mike
 
A Repair done properly would be safe forever and would not for any reason require a new engine mount. If we had to replace the center frame or tail boom everytime we found a cracked or rusted tube on our Bell 47 helicopters there would not be any left flying in the world. Just a thought to safe you a whole bunch of money.
 
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